Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$172.26	12.224%	$193.3171	$193.32	$193.30	$193.30
Purchase #2	$222.33	9.371%	$243.1645	$243.16	$243.15	$243.20
Purchase #3	$166.25	3.674%	$172.358	$172.36	$172.35	$172.40
Purchase #4	$97.27	11.834%	$108.7809	$108.78	$108.80	$108.80
Purchase #5	$9.80	4.588%	$10.2496	$10.25	$10.25	$10.20
Purchase #6	$144.95	4.497%	$151.4684	$151.47	$151.45	$151.50
Purchase #7	$166.78	11.330%	$185.6762	$185.68	$185.70	$185.70
7 purchase totals =	$979.64		$1,065.0147	$1,065.02	$1,065.00	$1,065.10